Weird Steering on a bike? Check the crown race

Tl;Dr: If your bike creaks or sticks when turning, see if the crown race is right side up

Steering on a bike is WAY more important than you think – than anybody thinks. This is because riding a bike is a constant unconscious process of extremely minor corrections to stay balanced. Here’s a great example: Backwards brain bicycle.

When something messes with steering, it’s usually catastrophic – you can’t turn at all, or the wheel fails to follow handle bars input. But minor disturbances are possible too and just feel indescribably yucky.

Take for example an upside down crown race. The handles bars are connected to the forks (and wheel) by a stem and a steering tube. The steering tube rests (bears) on the headset: an upper and lower bearing that allow the steerer to turn freely. Importantly, the steerer bears on 2 separate axes – horizontally the headset bearings allow the steering tube to rotate easily; vertically the crown race bears on the lower headset bearing to allow the fork to rotate easily in relationship to the head tube. Pretty much universally, the crown race interfaces with the Angeled surface of the lower headset bearing.

A very long way of saying: the Fork needs a specially machined crown race that has an angle that meets the bearing.

And crown race all have these! On One Side! The opposite side is usually just square. If an inexperienced assembler is putting a bike together, putting in on upside down would be an easy mistake. One you would recognize as soon as you took it for a ride.

Whoever assembled the bike we just got never took it for a ride. We got it at a bit of a discount because it had already been returned by one customer. The previous customer did take it for a ride and returned it because something was obviously wrong. But the manufacturer doesn’t seem to have been able to figure out what was wrong and so just put it back on the market.

After many hours of messing around, primarily thinking that The headset bearing itself was somehow ruined, I noticed that the crown race was not really snug against the top of the fork. Looking more carefully. I noticed that the top of the crown race did not have an angled surface, and must have been installed upside down.

The experience of writing a bike with an incorrect crown race is that the steering is a sticky. It’s possible to steer the bike, but you have to power through some friction before being able to start turning. Once you have all the inertia from powering the input to overcome the friction, then you have to back off so that you don’t over correct whatever you were trying to do. With the fine motions of balancing a bicycle. This is incredibly frustrating.

So, if you find the steering of a bicycle is weirdly sticky or off. Take a look at the crown race. Maybe it’s on upside down.